In recent years, special purpose catheter systems have been used to traverse and negotiate blood vessels for therapeutic as well as diagnostic purposes. Therapy is delivered via catheters both as an alternative to traditional surgery and as a means of last resort when surgery is not possible. Thus, embolization of selected blood vessels is sometimes performed in order to treat arterio-venous malformations and aneurysms, to block off the blood supply to tumors and to stop chronic bleeding. Other uses of catheters are to deliver chemotherapeutic agents and other substances to highly localized areas and to sample body fluids from remote spaces. More recently, balloon-type catheters have been used for treating stenoses in blood vessels as a means of relieving the constriction by physically expanding the vessel in the region of a stenosis.
Since the usefulness of the above forms of treatment is limited by the accessibility of the lesion to be treated, efforts have been made to develop catheters which can successfully penetrate ever deeper into the vascular system.
The basic problem is to advance a catheter through a narrow tortuous blood vessel without damaging the endothelium. Conventional catheters are often too large to fit inside the desired vessel or too rigid to negotiate the various twists and turns encountered in a particular vessel. Alternatively, they may be so flexible as to buckle instead of advancing into a remote vessel. Friction between the catheter and the vessel wall generally limits the length and number of curves through which a catheter can be pushed and even with balloon tipped catheters, which take advantage of flow to pull the catheters through tortuous vessels, their travel is limited by wall friction. Magnetically guided catheters are similarly limited and their overall complexity and expense limit their widespread application.
It is an object of the present invention to provide a method and apparatus for traversing blood vessels and which allows relatively deep penetration of the vascular system even through narrow and tortuous blood vessels.
More particularly, it is an object of the invention to provide a catheter arrangement particularly suitable for the use in traversing a blood vessel and which at least partially overcomes the problems associated with earlier catheter arrangements used for this purpose particularly as regards the matter of friction between the catheter and the vessel wall.
It is a further object of the invention to provide a catheter arrangement for use in the vascular system which facilitates movement of the catheter through a narrow or tortuous blood vessel to obtain access to relatively remote or inaccessible regions of the vessel.
Another object of the invention is to provide an improved method and means for traversing a blood vessel for therapeutic or diagnostic purposes.